Well..... It's been about 2 1/2 months since I first posted this so it's time for an updated. When I first posted here I also sent a link to this thread to SMP so they could hear other peoples comments also. Richard from SMP contacted me and said they were in the process of making their tanks with a different method to work with the ethanol in fuel. They were not yet ready then but they would send me one to test in the USA when they were available. I received one a few days ago and it will be going on a bike that still has the oil injection working and will be tested with straight pump gas.
Richard is very easy to deal with and said he had no problem with me experimenting with the tanks I already had while waiting on the new one. I rinsed the one with no sealer out with lacquer thinner and let it air out for a week. I then bought some Aviation Fuel LL100 (low lead 100 octane ) NO CORN. The carb got a full cleaning and a new filter installed. This fuel has now been in that tank at least a month and a half and has worked perfect, no residue, no pilot jet clogs, no problems at all.
I'll be trying the new tank out on pump gas and will pass on the results. If you have an older tank as others have said probably the best thing to do is use AvGas if you can and avoid the ethanol. Corn is for eating not adding to fuel!
Again Richard at SMP has been very helpful and concerned about keeping a customer happy. A refund was offered as well as the new tank. It's no fun to have a problem with a new part but it's good to know a vender will not leave you hanging.
The alcohol used in our fuels at about a 10% rate will deteriorate standard polyester fiberglass resin. Leaching polymers which wind up in carbs and engines. The fact it happened so quickly may be due to the fact the product was new and had not cured for ages, as it seems many report good results using the Caswells sealer in old succeptable tanks.
Ethyl alcohol is the cleanup liquid for poly resin, cuts it like a knife!
You need Avgas or race fuel to avoid the alcohol totally it seems, although there is a website that lists places where you can still get non-laced auto/ farm fuel, in rural areas.
Them guys making tanks need to go to a modern epoxy resin and get off the old standard poly stuff in this world for sure!
copemech I think you have hit the nail on the head. The world we live in and the fuels we use have changed. Ethanol is not new and people who are molding products made to hold fuel should be ahead of the curve not behind it. SMP has a lot of very useful products at very fair prices. I hope the tank issues can be worked out.
On of my TY250's has had an SM tank / seat unit on it since I bought it in 06. In 08 ish I had problems with small bits of the white plastic blocking the carb.I just gave it a good wash out and dried it throughly - no problems since.It often will sit for a month 1/2 full of fuel after a trial without being used.
A mate of mine has had terrible problems with all of his Whitehawks and even uses 4 star leaded petrol.
Other mates have complained about fuel going stale quickly causing problems with chainsaws too,mine dont seem to suffer at all.My fuel comes from the garage in the local village on account,I never take any notice of who delivers it.
I thought people were using leaded plane fuel to get over Ethanol problems because it is not included to stop icing.
We have had another TY 175 a few years ago that also had a SM seat/tank combo and it could sit for months with no problem. My Saracen has a 40 year old fiberglass tank on it that has the exact same fuel in it and I rode it yesterday with no problems and it has been sitting for weeks. My chainsaw and weed eater also work fine with fuel in them for weeks if not months.
My understanding is the ethanol may cause bubbling or soft spots over a long time. These tanks are brand new and had fuel in them less than a week. They are leaching some kind of very sticky substance all over the slide and throat of the carb in just a few days.
I have a sammy miller tank and seat unit like yours only mine is a fair bit older, never had any problems with it up until they started to add ethanol,then all of the problems you mentioned started. The solution is to drain the tank and leave the cap off to let the tank breath, remove the main jet from the carb and dump the fuel after riding.This is what I have been doing for about the last year and don't get any more problems.Im now running with a bigger pilot jet and a grade cooler plug because the motor was also running hotter than it use to, which I think is down to the petrol yet again.
Thanks for the reply Andy. I guess that could be an option. The first tank has hardened back up now that it has been sitting open and empty but that seems extreme for a brand new tank. After all it IS a fuel tank.
Is the sticky goop resin that is dissolving? Could a different resin be used?
First off this is not a slam against Sammy Miller Products as I have a lot of them on this bike. It is a request for help solving a problem.
This bike replaces my wife's old Montesa 123. She really like the looks of a tank/seat combo so a new one was ordered for the little TY. A US vendor that sells these recommends sealing them so I used a method that worked great on the Montesa tank.
The first weekend of riding the bike was great. After it sat for a week it would not run for her and I could tell the pilot was clogged. When cleaning it I found a fair amount of varnish on the slide. After the carb cleaning the bike ran fine for the rest of the day. The next day brought problems again. This time the bike would start and run but the throttle was sticking. Upon inspection the slide was covered with a very sticky varnish looking stuff. A look inside the tank brought horror! The sealer looked amber colored and was tacky to the touch. I could push my finger nail into it and scratch it and tank material away.
Well I manned up and assumed my sealer job failed and ruined the tank. I called SMP and told them what I had done and ordered another tank ($$$) and ask them if they had any thoughts on the problem. They said they had heard of ethanol problems but did not have any recommendations.
SMP really ship fast and the new tank was in my garage in just a few days. Not wanting to try (or able to afford)the sealer again I just rinsed the tank out with fuel and put it on the bike. Once again the little bike delivered a nice weekend of riding.
Well.... after setting for a few days and getting the bike out it did not run real crisp and a slight sticking of the throttle was noticed but I did not have time that day to look into it. The next day the bike would start but the throttle would stick horribly. Pulling the slide out showed even more sticky stuff on the slide and inside the carb. You could actually leave finger prints in it. pulling the fuel cap once again revealed horror! The inside of the tank had an amber color and I could scrape away a layer with my finger nail.
I made a call to SMP but they had no idea what was going on and had not had any other complaints, though mine had been the only tanks sent to the US recently. They want me to return the tanks for inspection which I will.
The fuel I put in them is just 91 octane regular pump fuel with Golden Spectro oil with a 50 to 1 mix that I use in everything I own, ie: bikes, chainsaw, weedeater, ect. I have the same fuel in my Saracen with a glass tank and no problems with it or the yard tools.
I have now put the stock tank back on and after cleaning the carb of the gunk (and hoping the gas would clean the gunk off the reeds and crank and bearings) The bike is working fine again using the exact same fuel from my storage can. I wish I had a way to send SMP some of the stuff I dumped from the tanks.
Any thoughts would be appreciated. I am going to send a link of this thread to SMP so maybe they can get some ideas.
Your bike for sure started out as a Wassell Antelope trials bike but has been altered to make it more like a trail bike. You already mentioned the seat and tail light, other things are the exhaust extension,chain guard, and head light. Other than that it looks pretty complete.
I have owned about ten of these sold as Penton Trials here in the states. Nice find.
Thanks for the info guys. I was pretty sure this was an after market plate. It is heavy, I weighed the thing and it is 4#. When I took it off the bike you could see that the oil pump cover had been cracked and welded back up. I would guess that was when this unit was installed.
Tony I hope you don't mind if our Yamahas come out looking a lot like yours as your blog has become my instruction manual for building them I sure wish I had got into Yamys when you were building and selling them. It would have been a lot easier and probably cheaper.
My new project is a 74 TY 250. I thought the skid plate on it was one of the fiberglass/plastic stock ones but when I took it off it turned out to be a cast aluminum one. I have saw stamped alloy ones but never cast. It has some embossed lettering that says J & M PLATES with Yamaha under that. Have any of you TY gurus seen these?
Here is a pic of the Mrs' new to her TY 175. After giving it a good cleaning and adjusting everything up I replaced all the fasteners with new stainless ones and added the Sammy Miller tank/seat combo and new yellow fenders.
She was anxious to play with it so I will wait till next winter to do a tear down and repaint the frame and go through the motor.
I ordered a tank/seat combo, front and rear mud gaurds and some other bits from Sammy Miller Products. The package shipped from the UK on Tuesday and was delivered to me in Missouri USA mid morning Thursday. Incredible
I normally just turn a new shock mount up on the lathe and weld it to the frame. Just remember to gusset the frame tube to the horizontal tube to dissipate the shock load. Dead easy.
Thanks, sounds simple enough. I would still like to see some pics of different bikes.
Your bikes are my inspiration to build a TY , since finding it I can't stop reading your blogs. I have been away from vintage trials for a few years and want to get back into it on something other than the British kit bikes I have been so fond of.
I have been looking at pictures of forward mounted shocks and it seems to be 3 schools of thought. 1, a saddle with post welded to the down tube, 2, a hole drilled through the down tube with a sleeve welded in to accept a through bolt, or 3, a gusset with a post welded to the back of the down tube.
What I would really like to know is which is best (or easiest) to do and see some close up pictures. I really would like to get this part done right the first time.
Would any of you Yamaha guys have any or be able to take some close up pictures of how your upper shock mount has been moved forward.
I would like to do this mod to my 250 and would like to see how others have done it. Please post pics here or you can email me direct at drwassell@charter.net
Kanur Get in touch with me anytime. Not too many Saracen owners out there. I know Paul Danik has a Saracen MX bike
I recently acquired a Saracen parts bike that was being sold as a trials model. After my friend picked it up and sent me better pictures it turns out it is an enduro model. I do not have it home yet but I am hoping it is savable.
I have a Pathfinder trials in running condition. I have not competed on it yet but the prior owner did. So far I just ride it on my property. It has better pegs that have been lowered slightly and the ignition has been replaced with a PVL. Puch engine parts or rebuilds are pretty easy to get over here but the Greeves guy in California doesn't consider them a real Greeves and is now help at all. Actually he is down right rude if you ask him about the Pathfinder.
I sure wish I had got into Yamys when you were building and selling them. It would have been a lot easier and probably cheaper.
to do and see some close up pictures. I really would like to get this part done right the first time. 
Picked Up a Real Cream Puff Yesterday
in Twinshock
Posted · Edited by kanur
Sprite! I think this model may be called a Goldfinger but I could be wrong.
I'm a real sucker for these British kit bikes